A vehicle has an exhaust aftertreatment system including an LNT. The vehicle operates through a series of ignition cycles, deNOX cycles, and deSOX cycles. DeNOX operations begin when the LNT reaches a loading threshold. The applicable threshold depends on operating conditions, such as mean LNT temperature and mean exhaust flow rate. The thresholds are adapted based on NOX removal efficiency data. The data is compared to target values. The target values depend on the operating condition range, but remain fixed while the thresholds are adapted. NOX removal efficiency is measured over intervals corresponding to entire deNOX cycles. The data is sorted into bins according to operating conditions. The adaptations are only made if a bin has several data points accumulated over a minimum interval that is at least one ignition or deSOX cycle, preferably several. The method provides stable adaptations that compensate for aging.